Spatial and temporal heterogeneity of soil respiration in a bare-soil Mediterranean olive grove
<p>Soil respiration (<span class="inline-formula"><i>R</i><sub>s</sub></span>) is an important carbon flux in terrestrial ecosystems, and knowledge about this CO<span class="inline-formula"><sub>2</sub></span> rele...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-02-01
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| Series: | SOIL |
| Online Access: | https://soil.copernicus.org/articles/11/213/2025/soil-11-213-2025.pdf |
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| Summary: | <p>Soil respiration (<span class="inline-formula"><i>R</i><sub>s</sub></span>) is an important carbon flux in terrestrial ecosystems, and knowledge about this CO<span class="inline-formula"><sub>2</sub></span> release process and the drivers involved is a key topic in the context of global change. However, temporal and spatial variability has not been studied extensively in semi-arid systems such as olive groves. In this study, we show a full year of continuous measurements of <span class="inline-formula"><i>R</i><sub>s</sub></span> with six automatic chambers in a fertigated olive grove with bare soil in the Mediterranean accompanied by modeled ecosystem respiration (<span class="inline-formula"><i>R</i><sub>eco</sub></span>) estimated by decomposing net ecosystem exchange (NEE) measured using the eddy covariance (EC) technique. To study spatial variability, the automatic chambers were distributed equally under the canopy (<span class="inline-formula"><i>R</i><sub>s Under-Tree</sub></span>) and in the center of the alley (<span class="inline-formula"><i>R</i><sub>s Alley</sub></span>), and the gradient of <span class="inline-formula"><i>R</i><sub>s</sub></span> between both locations was measured in several manual campaigns in addition to angular changes about the olive trees. The results indicate that <span class="inline-formula"><i>R</i><sub>s Under-Tree</sub></span> was 3 times higher than <span class="inline-formula"><i>R</i><sub>s Alley</sub></span> in the annual computations. Higher <span class="inline-formula"><i>R</i><sub>s</sub></span> was found on the southern face, and an exponential decay of <span class="inline-formula"><i>R</i><sub>s</sub></span> was observed until the alley's center was reached. These spatial changes were used to weigh and project <span class="inline-formula"><i>R</i><sub>s</sub></span> onto the ecosystem scale, whose annual balance was 1.6–2.3 times higher than the <span class="inline-formula"><i>R</i><sub>eco</sub></span> estimated using EC-derived models. <span class="inline-formula"><i>R</i><sub>s Under-Tree</sub></span> represented 39 % of the <span class="inline-formula"><i>R</i><sub>s</sub></span> of the olive grove. We found values of <span class="inline-formula"><i>Q</i><sub>10</sub><1</span> in the vicinity of the olive tree in the warm period. Outbursts of CO<span class="inline-formula"><sub>2</sub></span> emissions associated with precipitation events were detected, especially in the alley, during dry periods and after extended periods without rain, but they were not accurately detected by EC-derived respiration models. We point out an interaction between several effects that vary in time, that are different under the canopy than in the alleys, and that the accepted models for estimating <span class="inline-formula"><i>Q</i><sub>10</sub></span> and <span class="inline-formula"><i>R</i><sub>eco</sub></span> do not consider. These results show high spatial and temporal heterogeneity in soil respiration and the factors involved, which must be considered in future works in semi-arid agroecosystems.</p> |
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| ISSN: | 2199-3971 2199-398X |